Yun "TaeJa" Young Seo is a professional Terran player from South Korea, who is currently playing for Team Liquid.
Without any competitive background in e-sports, TaeJa began his progamer career during the summer of 2010 and remained a relatively unknown player for roughly ten months despite qualifying for the first ever season of the GSL. He started to make a name for himself after he joined team SlayerS in May 2011, as he achieved two all-kills in the GSTL and made his first appearance in Code S at age sixteen in the GSL October. Toward the end of the year and in early 2012, he completed a string of victories in ESV TV Korean Weeklies, but found himself unable of delivering noteworthy performances in offline events as well, dropping into Code A in December.
TaeJa signed for Team Liquid in March 2012, and rose to prominence during the next months. During the summer, he carried his team to the finals of the IPL Team Arena Challenge 3, achieving an unprecedented 23-3 record in the league. He became successful in individual tournaments as well starting this period, winning the MLG Summer Arena, the Assembly Summer 2012 and the DreamHack Open Valencia 2012, and reaching the semifinals of the MLG Summer Championship and of the GSL Season 4 – Code S.
When he was in kindergarten, TaeJa's parents ran a PC Bang (a South Korean LAN gaming center), where he encountered StarCraft: Brood War. He first tried StarCraft II when the open beta started in August 2010, and ended up placing high on the ladder. While he was debating whether he should pursue gaming or continue his studies, his South Korean teacher suggested he try out for the GSL preliminaries. He was able to make it through the qualifiers, and made his GSL debut that way. He resumed his studies after that, but felt that it just didn't fit him. His parents were very against it when he told them he would play StarCraft II professionally, but with his brother's help he was able to become a progamer.
 Wings of Liberty
 First Year as a Minor Player (Sep 2010 — Sep 2011)
TaeJa's first official StarCraft II match took place in the GSL Open Season 1 in September 2010. Then a member of the South Korean clan NEX, he was granted a defwin in the first round, and met FruitDealer in the round of 32. The Zerg player, who would later win the entire tournament, handily won the series and eliminated TaeJa from the league. A month later, on October 18, NEX merged with clan Zenith to become team ZeNEX.
“Back then, I was studying hard, even staying for evening study sessions at school. I was barely able to practice, so I told myself I'd just participate [in the GSL Open Season 1] for the sake of the experience. I got a walkover in the RO64, so I think I got too nervous for the RO32 match. Since then, I always tell myself not to get nervous when I play games.”
TaeJa, who had failed to qualify for GSL Open Season 2 and 3, found himself tied with twenty-one other players in the 2010 GSL rankings. GOMTV organised tiebreakers in December to determine which of them would be seeded in the upcoming 2011 GSL January Code A, and TaeJa failed to earn a spot. In January 2011, he was used by ZeNEX in the Zotac Team Invitational Season 2 Group Stage, delivering an unimpressive performance with a 2-4 record. In March, TaeJa failed to qualify for the 2011 GSL May, losing to SuHoSin in the preliminaries. At the end of the month, he was reported to have left team ZeNEX, and later joined SlayerS at an unknown date in April or May 2011. However, he didn't move into SlayerS team house, preferring his own individual practice routine. TaeJa made his first apparition in his new colors in the best possible way, all-killing his former team ZeNEX (beating Puzzle, CoCa, ByuN, and Kyrix) in the GSTL May (an achievement that would remain his most memorable moment with team SlayerS upon leaving it in March 2012). SlayerS eventually won the league, with TaeJa playing only one more game which he lost to Leenock. Later in May, he bested his teammates in the Clash of the Houses: SlayerS, hence earning a spot in the main event which featured a paid trip to the 2011 MLG Columbus for its winner. In this event, he made his way to the finals at the expense of MarineKing and GuMiho (who then was a Random player), only to narrowly lose to July and to miss his opportunity to attend a live foreign event.
TaeJa, who had still yet to qualify for the GSL Code A, attended the LG Cinema 3D Special League in June 2011 after winning his regional qualifier. His run in the tournament was short-lived though, as DongRaeGu eliminated him in the first round. Two months later, he finally qualified for the GSL at the expense of BBoongBBoong, earning a spot in the 2011 GSL August Code A (which would be his first participation in the league since the 2010 Open Season 1 more than a year before). TaeJa's debut in Code A was almost flawless, as he defeated TAiLS, sC and JYP in order to reach the semifinals. Before that match actually occurred, TaeJa achieved the second all-kill of his career, beating SocceR, Moon, ThorZaIN and NaNiwa of team F.United in the 2011 GSTL Season 1 group stage. This all-kill would be the only victory for SlayerS during this season of the GSTL, the team eventually ending up at the last place of its group. A few days later, on August 22, TaeJa was swept 3-0 by GanZi in the Code A semifinals, meaning that he would still have the opportunity of earning a Code S spot via the upcoming up & down matches played in early September. He placed first in his group, qualifying for the next Code S season. TaeJa was successful in the WCG 2011 Qualifiers as well, beating Sniper and GuMiho to proceed to the round of 16.